De-stressing the Brain: Can Eating Grapes During Periods of Mental Stress Protect Brain and Vascular Health in Young Adults

Psychological stress is widespread in our societies, and has been extensively shown to have negative consequences for human health. Specifically, psychological stress induces significant declines in human vascular function, as measured by brachial Flow-mediated Dilatation (FMD). We have demonstrated that flavonoid interventions can prevent the harmful effects of stress on the vascular system. Indeed, flavonoid-rich interventions have also been extensively shown to improve peripheral and cerebrovascular function in the absence of stress. However, the effect of flavonoids on cerebrovascular function and cognition in the context of mental stress is unknown. In the proposed project, our key objectives are to investigate whether grape intake prior to a mental stress task results in better brain oxygenation and vascular function, which leads to improved cognitive performance and mood in young healthy adults. These data will establish whether grapes can be effective as a 'stress snack' to optimize cognitive and brain function in the context of psychological stress. Furthermore, we will explore whether there are certain participant characteristics that mediate the impact of grape flavonoids on cerebrovascular function and cognition in the context of mental stress. Such as, physical fitness (assessed by a VO2 max test), composition of gut microbiome (assessed by faecal sample), habitual diet (assessed by 3-day food diary and the food frequency questionnaire), and eating behaviour and chronic stress (assessed by the eating behaviour questionnaire and perceived stress scale). This work will be important to guide future dietary recommendations around stress and might ultimately result in increased intake of flavonoid-rich grapes and other flavonoid-rich fruits/vegetables overall.

• Flow-mediated dilatation (FMD) of the brachial artery [Time frame: Change from pre-intervention baseline to 2 hours and 2 hours 45 minutes post-intervention (45-90 minutes post-stress).]
• Common Carotid Artery (CCA) - Blood flow [Time frame: Change from pre-intervention baseline to 2 hours and 2 hours 45 minutes post-intervention (45-90 minutes post-stress).]
• Common Carotid Artery (CCA) - Shear rate [Time frame: Change from pre-intervention baseline to 2 hours and 2 hours 45 minutes post-intervention (45-90 minutes post-stress).]
• Executive Function (MANT) - Accuracy [Time frame: Change from pre-intervention baseline to 1 hour 15 minutes post-intervention (10 minutes post-stress).]
• Executive Function (Switch) - Accuracy [Time frame: Change from pre-intervention baseline to 1 hour 15 minutes post-intervention (10 minutes post-stress).]
• Executive Function (MANT) - Reaction time [Time frame: Change from pre-intervention baseline to 1 hour 15 minutes post-intervention (10 minutes post-stress).]
• Executive Function (Switch) - Reaction time [Time frame: Change from pre-intervention baseline to 1 hour 15 minutes post-intervention (10 minutes post-stress).]
• Executive Function (MANT) - Inverse Efficiency Score [Time frame: Change from pre-intervention baseline to 1 hour 15 minutes post-intervention (10 minutes post-stress).]
• Executive Function (Switch) - Inverse Efficiency Score [Time frame: Change from pre-intervention baseline to 1 hour 15 minutes post-intervention (10 minutes post-stress).]
• Mood (POMS) [Time frame: Change from pre-intervention baseline to 1 hour post-intervention (immediately following stress), 2 hours and 2 hours 45 minutes post-intervention (45-90 minutes post-stress).]